Hydraulic pump or motor



Aug., 10, 1965 M. L. WOLF 3,199,461

HYDRAULIC PUMP OR MOTOR Filedmay 27, 196s 4 sheets-sheet 1 l Il 1/ l am 19.15;

INVENTOR. MARVIN L. WOLF IHM/1% ATTO'RN Aug 10, 1965 M. L. WOLF 3,199,461

HYDRAULIC PUMP 0R MOTOR Filed May 27, 1963 4 Sheets-Sheet 2 2Q Low al H 52` HIGH u gg 52 2l LOW 60 i6|/ HIGH 73 es 74 5o Low 72 75 HIGH S l 4| u L\\\\\\\\w F42 25 INVENTOR.

MARVIN L. WOLF BY l ATTORNEY Augo 10, 1965 M. L. WOLF 3,199,461

HYDRAULIC PUMP OR MOTOR Filed May 27, 1963 4 Sheets-Sheet 3 f' f 5| 2 0. 912 4 52 l.. 2 l' L/ 1k\ q Vgl 94 f 96 95 TW INVENTOR.

. MARVIN woLF 46 BY l ATT United States Patent O 3,1%,461 HYDRAULIC PUMP R MTOR Marvin L. Wolf, Hutchinson, Kans., assigner to The Cessna Aircraft Company, Wichita, Kaus., a corporation of Kansas Fiied May 27, 1963, Ser. No. 283,376 l2 Claims. (Cl. 10S-162) This invention relates generally to fluid pressure energy translating devices which are capable of either generating and delivering or receiving and utilizing high uid pressures.

More particularly this invention relates to multiple cylinder, reciprocating piston type, variable displacement pumps and motors, whether the cylinders are disposed parallel to the rotational axis of the cylinder block, or radially with respect to that axis of rotation.

In pumps and motors of the types mentioned above, rnoveA Lent of the cylinder block causes the open end of each piston chamber to successively register with a low pressure fluid port and with a high pressure uid port in the body of the pump or motor. When a piston chamber containing fluid under a different pressure (either too high or too low) registers with a high pressure port in the body, a distinct and often violent shock or hammer occurs. Such shocks cause physical damage to pump elements, cause premature wear, cause objectionable operational noise, and reduce the volumetric efficiency of the pump or motor.

It is a prime object of this invention to provide a structure and means for eliminating such shocks during pump or motor operation, and which accomplishes shock elimination by either decreasing or increasing the fluid pressure in each piston chamber just prior to its actual registry with the high pressure port in the pump or motor body, to thus substantially equalize the pressures in the high pressure port and in each approaching piston chamber before they are in open communication.

Another object is to provide a shock eliminating structure of the type referred to above which accomplishes the referred to pressure equalization by either adding pressurized Huid to or receiving pressurized iiuid from each piston chamber after it has broken communication with the low pressure port in the pump or motor body, and prior to its registry with the high pressure port therein.

An additional object of the invention is to provide an increase or decrease in pressure and fluid volume in each piston chamber of a variable volume hydraulic pump or motor, even though the piston stroke is set at minimum length.

A still further object of the invention is to provide a means for precisely controlling the rate and degree of pressure rise in each piston chamber of a variable piston stroke pump during the time the piston chamber is traveling from the low pressure port in the pump body to the high pressure port therein, regardless of the variation in the length of piston stroke, and regardless of the length of the land between the low and high pressure ports.

Another object is to provide a structure capable of substantially equalizing the pressures in a high pressure body port and an approaching piston chamber, prior to registry of the two, whether in a pump or a motor, and whether the pump or motor is operating in a clockwise or counter/clockwise direction of rotation.

Mdel

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Still another object is to provide a structure capable of incorporation into a multiple piston type hydraulic pump in which the pistons are reciprocated by Contact with a movable cam, and in which the cam can be moved to reverse the phase of piston reciprocation to thereby reverse the direction of ow of fluid to and from the pump body, and in which the incorporated structure embodying this invention serves to equalize the pressures in the high pressure port and in each approaching piston chamber, prior to registry of the two, regardless of the direction of i'iow of fluid to and from the pump.

Further objects and advantages of the invention will be apparent when the following description is read in connection with the accompanying drawings, in which:

FIG. l is a central transverse sectional view through one type of multiple piston variable volume uid pressure energy translating device embodying my invention;

FIG. 2 is a fragmentary iiat pattern sectional view through the FIG. 1 device and shows a stationary portion of the body, and a portion of a rotating cylinder block, as well as the details of construction of one embodiment of my invention;

FIG. 3 is a View similar to FIG. 2 but shows the cylinder block in a different position with relation to the body section;

FIG. 4 is a top plan view of a ported valve plate for installation in a fluid pressure energy translating device which is incapable of reversing the direction of fluid flow therefrom;

FIG. 5 is a top plan view of a ported valve plate for a pump such as shown in FIG. 1, which is capable of reversing the direction of fluid ow therefrom by reversal of cam inclination;

FIGS. 6 and 7 are fragmentary flat pattern sectional views similar to FIGS. 2 and 3, and illustrate a variation in structural details which constitutes a second embodiment of the invention;

FIG. 8 is a view similar to FIGS. 6 and 7, and illustrates a valve plate which has a different porting arrangement than the valve plates in the Vother views;

FIG. 9 is a fragmentary iiat pattern sectional view of a fluid pressure energy translating device which includes structure which constitutes a third embodiment of my invention;

FIG. 10 is a view similar to FIG. 9, and shows one embodiment of my invention incorporated in a uni-rotational uid driven multi-piston motor;

FIG. 1l is a top plan view of a ported valve plate shown in the FIG. l0 motor;

FIG. 12 is a fragmentary flat pattern sectional View through a uid pressure energy translating device of the multiple piston variable displacement type capable of being operated in either direction of rotor rotation, and either `as a pump or as a motor, and embodying my invention in a fourth form;

FIG. 13 is a top plan view of a ported valve plate for the FIG. 12 device; and

FIG. 14 is a fragmentary transverse sectional through a fluid pressure energy translating device of the multiple piston variable displacement type embodying my invention, but which has its cylinders arranged radially with respect to the axis of rotation of the cylinder block.

FIG. l illustrates only one of many types of hydraulic energy translating devices in which my invention may be embodied. The FIG. l device is an axial piston type s hydraulic pump so designed that iiuid pressurized therein can be selectively delivered from either of two ducts Ztl or 2l in the pump body.

The pump body or housing includes a generally cylindrical, hollow intermediate section 22, an end or bottom section 23, and an end or head section 2d.

A rotor in the form of a cylinder block 25 is journaled by body section 22, and is rigidly secured on a central drive shaft 26 which is journalcd in bearing 2,7 in body section 243.

Cylinder block 2S is provided with a plurality of cylinder bores 23 disposed parallel to the rotational axis 26, and spaced concentrically around that axis. Each bore 2S is provided with a piston 29 which extends from the lower end of its bore and is connected by a conventional ball joint 3d to a shoe 3l. The respective shoes are held in their proper relative positions, as the cylinder block is rotated, by a pressure plate 32, which centrally seats and is urged downward by a spring pressed plunger 33, mounted in a recess in the lower end of shaft 26.

The lower surfaces of shoes Si are thus spring urged into positive slidable contact with the upper surface of a piston reciprocating cam plate 3d. Plate 34 seats on and is tiltable in either direction about the cross sectionally semi-circular head oi a transversely disposed fixed tongue 35, by means of controlled hydraulically r air pressure actuated cooperating pistons 316 and 37, mountedV in bores in the end section 23, connected respectively with pressure ducts 38 and 39.

From FlG. 1, it will be seen that the upper end of cylinder block is planar, and seats positively but slidably against the planar lower surface of a valve plate di), having arcuate ports il and 42, which serve to con- .trol and time the flow of fluid between the piston chambers 2% and the ducts 2d and 2li.

Ey forming the ports dl and 42 in an integral part lof head section 24, the valve plate, as a separate element, can be eliminated. Such separate plates are ordinarily provided, however, to permit plate replacement; to afford reversing of the direction of rotation of the rotor, if required; to afford conversion of the pump to a motor, etc. The relative locations of the ports dll and 42, the distance between their respective adjacent ends, their relative lengths, etc., in relation to the reciprocation 'cycles of the respective pistons, together serve to time and govern the function of the device, as will be clearly understood by those familiar with this art.

It should also be understood that` some pump and Ymotor designs provide for the cylinder block to remain stationary, for the inclined cam plate to rotate with the driving or driven shaft, as the case may be, and for the valve plate to either rotate` with the driving or driven shaft, or to be rotated or oscillated by separate but coordinated mechanism. My invention is capable of being embodied in all such designs.

Referring now to drawing FGS. 2, 3 and 5, FIG. 5 illustrates the arrangement, size, spacing, etc., of the ports dit and 4t2 in the valve plate dil, which ports communicate respectively with the ducts 2t) and 2l. This particular valve plate is designed to cause the liuid pressure energy translating devi of FiG. l to function as a pump for taking in liquid under low or atmospheric ypressure and for delivering that liquid under high pressure. The View of the valve plate is from its upper surface.

Valve plate 4d is indexed in the pump body so that as each piston reaches dead center at the end of its intake stroke the piston chamber for that piston has just broken its communication with the low pressure port 4l, and is in the relative position indicated by the broken line circle 43, assuming that the cylinder block is rotating in the direction indicated by the arrows in FIGS. 2, 3, and 5, and that the inclination of cam plate 31- is as shown in FIG. 1. Similarly, as each piston reaches a dead center position at the end of its uid discharge stroke, the open end of the piston chamber is in the relative position indicated by the broken line circle d4, having just broken its communication with the adjacent end of high pressure port 42.

My invention includes the provision of additional ports 45 and d6 in valve plate di), in the relative positions shown. lt also includes correspondingly located pressure control chambers 47 and 4S in body section 21,-com municating with ports i5 and de respectively, and through those ports with the piston chambers in the cylinder block 2S, as they pass the respective ports.

The chambers 47 and i8 are in communication with the adjacent ducts Ztl and 2l respectively by means of ducts i9 and 5d (FlG, 5). Each of the pressure control chambers 47 and d3 is divided by a movable barrier 51 (HG. 2) into a pressure regulating compartment 52, and a pressure regulation assisting compartment in the FIG. 2 embodiment of the invention the barrier is in the form of a small skirted plunger which slidably seals against the wall surface of its cylindrical chamber 48, and which is normally urged by a coil spring S4 against a travel limiting stop 55.

Operation as a pump with single direction of rotation (FIGS. I, 2 3, and 5) When the FIG. 5 valve plate is installed in the FIG. 1 device, it can function only as a pump.

When shaft 26 and the attached cylinder block 25 are rotated, the pistons 29 are caused by inclined cam plate 3d to reciprocate, and the respective piston cham bers register successively with the valve plate ports di, d6, 42 and 45 (FIG. 5).

As each piston chamber is disconnected from the low pressure intake port dll its piston has just reached the end of its suction stroke (dead center) and is in the relative position identied by the numeral e3 in FlGS. 2 and 5. As cylinder block movement continues'the piston starts its compression stroke.

The degree of compression of the iluid in the piston chamber is a function of the stroke length movement of the piston between the time it starts its compression stroke and the instant the piston chamber rst communicates withl the high pressure discharge port (i2. if the cam inclination angle is high, the piston stroke length is relatively long, and iluid compression is high.

During this travel of the piston chamber it communicates with pressure regulating chamber S2 (FlG. 2) through valve plate port 46. It the iiuid pressure in the piston chamber becomes higher than the pressure existing in high pressure duct 2i (HG. 2) then the pressure differential existing on opposite sides of barrier Si forces thatbarrier slightly away from the piston and forces a minute quantity oi i'luid into pressure regulating compartment 52, thereby reducing the pressure in the piston chamber until it equals the pressure in duct 2l plus the slight force exerted by coil spring 5d on the barrier 5i. The pressures in the piston chamber and in high pressure duct 21 are thus substantially equalized prior to initial registry of the piston chamber with the duct 2l, and the undesirable and damaging effects of shock are eliminated.

As piston chamber movement continues until it is in the position indicated by numeral Sd in FiG. 3, the piston chamber opening bridges the land between valve plate ports 46 and d2. In this position the piston chamber is in communication, with the pressure regulating compartment S2 and also with high pressure discharge duct 2li. Excess iuid which may have entered cornpartment 52 during the pressure equalizing function is forced back out of compartment d2 into the high pressure duct 2l by the action of spring 5d on the barrier dit, and the barrier returns to its normal position, as in FIG. 3, ready to equalize the pressure in the next approaching piston chamber.

As piston chamber movement continues around the FIG. 5 valve plate, the piston completes its fluid discharge stroke and starts its suction stroke at position 44. The pressure on any high pressure fiuid then trapped in the piston chamber is reduced by suction stroke movement of the piston during the time the piston chamber travels from position 44 to a point of its initial communication with low pressure port 41. The pressure regulating unit which communicates with port 45 -is ineffective and unaffected during the last described portion of piston chamber movement. Since the pressure in the piston chamber is reduced substantially to the pressure in low pressure duct 29 prior to their initial communication, there is no shock due to differential pressures.

The piston chamber pressure regulating unit designated by numeral 47 in FIG. 5 is effective only when the piston actuating cam 34 (FIG. 1) is tilted in a direction opposite to that shown in FIG. l. Reverse tilting of the cam causes a 180 change in piston cycling, and consequently reverses the direction of fluid flow from the pump. Duct 21 becomes a low pressure or intake port, and duct 29 becomes the high pressure discharge port. Pressure control unit 48 then becomes ineffective, and unit 47 assumes the pressure regulating function, as previously described. Such reversal of fluid flow from the pump is necessary when the pump is driving a fiuid mot-or, and when it is desired to reverse the direction of rotation of the fiuid motor.

If no reversal of fluid iiow from the pump is required, or if the pump is not constructed so that its cam tilt direction can be reversed, then the valve plate of FIG. 4 can be used, and only one pressure control chamber 43 is required in the head 24.

FIGS. 6 and 7 If the service for which the pump is intended frequently requires extremely short piston strokes (cam inclination angle almost perpendicular to the rotational axis of the cylinder block) then the pressure rise in each piston chamber as it travels from position 43 in FIGS. 2 and 5 to position 56 in FIG. 3 is sometimes not sufficiently rapid to raise the piston chamber pressure to the pressure in the high pressure discharge duct 21 by the time the piston chamber initially communicates with that duct. To obviate this difiiculty the modifications shown in either FIG. 6 or FIG. 7 may be used. The two are equivalent in function.

In the FIG. 6 pressure control unit a tiny orifice 57 is provided in barrier 51 to supply supplemental fluid to each piston chamber while it is in communication with the pressure regulating compartment S2. The orifice size is such as to prevent a rapid fiow of fluid from duct 21 through duct Sti and through the orifice to the piston chamber. If the pressure in the piston chamber is not rising fast enough, due to short piston stroke, the fiow of supplemental fluid through orifice 57 will cause an increase in the rate of pressure rise sufficient to cause the piston chamber pressure to be at or very near the pressure in the high pressure duct 21 at the time the piston initially communicates with that duct.

The FIG. 7 configuration functions in the manner just described above, and differs from the FIG. 6 conguration by the substitution of a small flow area orifice duct S3 for the orifice 57 in the barrier 51. Duct 58 permits the fiow of a very limited quantity of supplemental fluid from high pressure duct 21 directly to pressure regulating chamber 52, and to the piston chamber 59 prior to its registry with duct 21 in body 24.

FIG. 8

A variation in valve parts porting only is shown in FIG. 8. Here a tiny fiow orice 60 and a relatively small diameter port 61, both in valve plate 4t), are substituted for the single large diameter port 46 shown in FIGS. 2 to 7 inclusive. The purpose of this alternate porting is to provide a precise control over the rate of pressure rise in each piston chamber as it travels from 10W pressure duct 20 to high pressure duct 21, during the compression stroke of the piston.

Orice et), due to its small fiow area, provides a finely .metered fiow of fiuid in either direction between each piston and the pressure regulating compartment 52 during their registry, and before registry of the piston chamber with port 61. The flow through two such orifices, arranged in series, is well understood by those familiar with this art. By selection of proper orifice size, location, spacing and phasing or'indexing with respect to the ducts 20 and 21, the fluid compression rate may be tailored to obtain almost any desired characteristic, regardless of the magnitude of piston stroke. Due to the minute quantity of supplemental fluid required in each piston chamber to provide the desired compression when the piston stroke is at or near zero, the size of orifice 60 is small enough that its action predominates only when piston stroke length is very small. At longer piston stroke the pressure control units previously described perform the compression controlling or equalizing function.

FIG. 9 embodiment FIG. 9 illustrates a second embodiment of my overpressurization and underpressurization controlling invention. As in the first described embodiment it includes a pressure control chamber 6&3 located in the pump body 24, between the low pressure port 20 and the high pressure port 21. Chamber 68 is divided by a movable barrier 71 into pressure regulating compartment 72 and a pressure regulation assisting compartment '73. In the FIG. 9 embodiment the barrier '71 is molded in general hat section form from a liquid impervious neoprene or plastic material which has a strong tendency to return to its original molded conguration after being deformed, stretched or otherwise moved from its stable equilibrium position, in which it is shown in FIG. 9.

Barrier 71 is sandwiched between formed perforated sheet metal or screen wire stops 74 and '75 which serve to limit the movement of the central portion of barrier 71 due to pressure differential in chambers 72 and 73.

The diaphragm type barrier 71 and its two movement limit-ing stops are all formed with nesting skirts, as shown, which seat on the inner end of a threaded insert 76. A conventional neoprene O-ring 77 surrounds the assembled skirts and is compressed to seal against the wall of chamber 63 when insert '76 is threaded tightly into the threaded open end of that chamber.

Operati0n-FIG. 9 embodiment The operation of this embdiment of the invention is almost the same as the operation of the FIG. 2 embodiment with the spring pressed plunger 51.

During the compression stroke of each piston, as the piston chamber travels from duct 2t) to duct 21, the pressures in duct 21 and in the piston chamber are equalized before the piston first communicates with the duct 21, during communication of the piston chamber with the pressure regulating compartment 72. If the pressure in the communicating piston chamber is lower than the pressure in duct 21, then the higher pressure in assisting chamber 73 is translated, by barrier movement toward its stop 7S, to the regulating compartment 72 and to the piston chamber. As the piston chamber moves on toward duct 21 it bridges the land in the valve plate between ports 46 and d2, and the barrier 7S returns to its position of stable equilibrium. Any fluid lost from compartment 72 during its pressure equalizing function is replaced during the time compartment 72 and duct 21 are in communication through the land bridging piston chamber opening.

Similarly if the pressure in the piston chamber is higher than the pressure in duct 21, the flexible barrier 71 is deflected toward its stop 74 until the pressures in the aros/ier piston chamber and in duct 2li are equalized. Excess fluid in regulating compartment i2 passes to duct 2l as the piston chamber opening bridges the valve plate land and Vaiiords. momentary open communication ctv/een regulating compartment 72 and duct 2li. Barrier 7l returns to its position of stable equilibrium, and is ready for its new pressure equalizing cycle.

It will be apparent that it supplemental rluid is desired it can be supplied by providing an oriice in the central portion of the barrier '71, such as described in connection with the modication shown in FlG. 6. Tie function and `operation would be the same. Alternatively, the duct shown in FIG. 7 could be used. Also the dual valve plate ports o@ and di (Fli. 8) could be substituted for the single large port 46, in connection with the PEG. 9 embodiment.

Adaptation to fluid driven motor FGS. l0 and 1l illustrate the invention as applied t a iiuid driven motor, as distinguished from a pump. The pressure equalizing structure shown is the same as the structure illustrated in FlG. 2, but the FIG. 9 structure could be substituted. The primary difference is in the porting and indexing of the valve plate 725, as shown in PEG. l1.

In a counterclocliwise rotating motor the high pressure port 7@ becomes the inlet port, and low pressure port Sil becomes the discharge port. These ports, and the intermediate valve plate port Si are of such length and are so arranged, and the valve plate is so indexed with respect to the stroke cycles of the pistons, that as each piston chamber reaches the position indicated by the broken line circle SZ, the piston in that chamber is still traveling on its discharge or compression stroke.

As the piston chamber breaks its communication with low pressure port it@ and travels toward port 8l to the position 83 (FIG. 1l), the piston in the chamber completes its compression stroke, compressing the iluid contained in the piston chamber at the time the chamber brol-:e communication With the llotv pressure port If too much or too little compression has occurred, cornmunication of the piston chamber with the pressure regulating compartment 52, through port Sil, serves to substantially equalize the pressures in the piston chamber and in high pressure duct 2l before the two actually communicate, as previously described. Shock is thus eliminatcd.

FIGS. l2 and 13 illustrate one means for adapting the previously described pressure regulating structures ci` PEG. 2 or 9 to a iuid pump or motor which is capable or operating in either direction of rotation.

Reierring to FG. 12 the plunger type barrier Sli divides the pressure control chamber into the pressure regulating compartment 52 and the regulation assisting compartment 53, as previously described in connection with FIG. 2. The spring and stop arrangement are the same as for the FlG. 2 embodiment.

A tloating piston de is reciprocable in a cylinder 85 formed in the body section 24. Intermediate its ends, cylinder 35 communicates with compartment 53 by means of a duct do. At its opposite ends cylinder 35 communicates with body duct 2G through a duct 87, and with body duct 2l through a duct 83.

A duct d@ and a registering port 9@ in the valve plate 91 afford communication between the successive piston chambers 92 and cylinder 555, near its left end. Simi. larly a duct 93 and a registering valve plate port 9d afford communication between the successive piston chamber and theicylinder SS, near its right end. Note that the ports 9@ and 94 are suiiiciently near the central port id to be bridged by the piston chamber openings as they travel in either direction of rotation. Note also that tween the traveling piston chambers 92 in cylinder block and the ducts 2@ and El, respectively, in body 24. FIG. IZ-Operaon as Zai-.rotational motor Assume that the FlG. l2 structure is embodied in a birotational :fluid driven motor; that ducts Ztl and 2l are resp?:tivelyV low and high pressure ducts; and that the motor first oA crates in a countercloclzwise direction, as indicated by arrows 97 in FFSS. l2 and 13. Due to the higher pressure in duct Ztl the piston valve Will occupy the position shown in FiG. l2.

As each piston chamber opening is disconnected from low pressure duct 2i?, the piston in that chamber is vstill traveling axially on its compression or discharge stroke, and does not reach the end of its discharge stroke (dead center) until the piston chamber lhas reached the relative position indicated by the broken line circle 99 in FlG. i3. l ence fluid in the piston chamber is pre-compressed before the piston chamber reaches position Q9. ln this position the piston chamber is in communication only with pressure regulating chamber 52, and with cylinder S5 and duct 2li only through the tiny orifice 57 in barrier piston 5l.

As the piston chamber travels from position 99 toward duct 2, the piston starts its power or intake stroke. During registry with pressure regulating compartment 52, the pressure in each successive piston chamber is raised by fluid pressure flow through orifice 57 and/ or lowered by movement of barrier piston 5l to the pressure existing in duct 2 and duct @Z5 so that when the piston chamber maires its Aoriginal registry with port @d the pressures are substaA y egual and shock is eliminated. A small amount of pressurized fluid will then enter the piston chamber through port 9d prior to the registry of the piston chamber and duct for the majority of the pistons power stroke. Barrier piston 5l is returned to piston stop 55 by spring 53 during the time that the piston chamber bridges the space between ports do and 94.

lf the rotational direction of the motor isrto be reversed, then high pressure motive fluid must be introduced into duct 2t?, and duct 21 becomes a low pressure discharge duct. Piston valve moves to `the right hand end of its cylinder 35 and blocks ducts d@ and 93. Since the porting arrangement is symmetrical, theV operation is the reverse of that just described above, the pressure in each piston chamber being equalized with the pressure in the high pressure duct by registry with port to prior to actual registry of the piston chamber with port El@ and subsequently with duct Ztl.

FIG. IZ-QpQrrzzon as ibi-rotational pump The same structure (FlGS. l2 and i3) serves for a birotational pump, it being necessary only to index the valve plate so that as each piston chamber is disconnected from the low pressure duct or 2l, depending on the direction of rotation or" the cylinder block), the piston inthe chamber has just comple-ted its suction or intake stroke, and starts its compression stroke. As the piston chamber travels toward the high pressure duct it communicates successively with the pressure regula-ting chamber 52, and through ducts be and 93 with the high pressure duct 2l, prior to actual direct communication Withthat duct. This prior communication substantially equalizes the pressure in each piston chamber and in the high pressure duct prior to their actual direct communication, thus eiidir ng hammer or shock due to pressure differences, as previously described.

FIG. 14--Radz'al piston pump or motor FIG. 14 illustrates one manner in which either of those embodiments of the invention illustrated in FIG. 2 or 9 may be adapted for use in a pump or motor which has radi-ally disposed cylinders in a cylinder block lil() which rotates about a stationary pintle 191. The pressure control chamber is located in the pintle, and is connected by a duct 102 with the high pressure duct 163. A port 104 is located to afford communication successively between the respective piston chambers and the pressure regulating compa-rtment, as the cylinder bl-ock rotates.

Operation to substantially equalize the pressures in each piston chamber and in the high pressure duct prior to their actual direct communication is identical to the operation previously described in connection with the FIG. 2 and FIG. 9 embodiments.

Having described the invention with rsufficient clarity to enable those familiar with this art to construct and use it, I claim:

1. In a multi-cylinder, reciprocating piston type fluid pressure energy translating device in which there is relative movement between a cylinder block and a fluid handling section which .defines internal, spaced, low and high pressure ducts, and in which such relative movement successively brings open ends of the piston chambers in the cylinder block into alternate open communication with the low and the high pressure ducts lin the fluid handling section, and in which piston rec-iprocation and the relative movement between the cylinder block and said fluid handling section is timed so that each piston travels on at least a portion of its compression stroke between the time its chamber breaks communication with said low pressure duct and the time its cham-ber begins direct communication with said high pressure duct,

structure for adjusting the pressure in each successive piston chamber to subs-tantially equal the pressure in said high pressure duct between the time each piston chamber breaks communication with the low pressure duct and the time it starts communication with said high pressure duct, comprising:

a liquid filled pressure control chamber located between said low and high pressure ducts defined by the said iluid handling section;

a differential pressure movable barrier traversing said control chamber and continuously dividing it into (a) a variable volume, piston chamber pressure regulating compartment, and

(b) a separate variable volume, pressure regulation assisting compartment,

said pressure regulating compartment having `an open port located to openly communicate with the open end of each successive piston chamber between the time the piston chamber breaks communication with said low pressure duct and the time the piston chamber begins direct communication with said high pressure duct; and

duct means affording open communication between said high pressure duct and said pressure regulation assisting compartment,

whereby, during the time each piston chamber is in communication with said pressure regulating compartment, the liquid in both is subjected, through the movable barrier, to the pressure existing in said high pressure duct, and vice versa, and the pressure on `the liquid in each successive piston chamber is thus adjusted, prior to the-start of its communication with .said high pressure duct, to substantially equal the pressure then existing in that duct.

2. The pressure regulating structure described in claim 1, and

means affording highly restricted but free liquid flow lbetween said high pressure duct and said pressure regulating compartment independent of any simultaneous communication between the high pressure .duct and the pressure regulating compartment through the lsucces-sive individual piston chambers.

3. The pressure regulating structure described in claim 1 in which said pressure control chamber has a cylindrical wall, and said movable barrier is a floating plunger therein.

d. The structure described in claim 3, and

fixed means in said pressure control chamber limiting the movement of said floating plunger in both directions.

5. T he structure described in claim Ll, and

spring means urging said plunger in a direction toward said pressure regulating compartment.

6. The pressure regulating structure described in claim l in which said movable barrier is a flexible diaphragm movable in said pressure control chamber from a position of stable equilibrium; and

means sealing `against liquid leakage between the pelripheral edge of said diaphragm and the adjacent wall surface of said pressure control chamber.

7. The structure described in claim 6, and

xed means disposed transversely in said control chamber on opposite sides of said diaphragm to limit its movement in either direction from its position of stable equilibrium.

8. In a multi-cylinder, reciprocating piston type fluid pressure energy translating device which includes a arousing enclosing a rotatable cylinder block, and a cooperating fixed uid handling section having internally open spaced low and high pressure ducts arranged to communicate alternately with open piston chambers in said cylinder block as the block rotates, and in which piston reciprocation and the rotational speed of the cylinder block is timed so that each piston travels on at least a portion of its compression stroke between the time its chamber breaks communication with said low pressure duct and the time its chamber begins direct communication with said high pressure duct,

structure for adjusting the pressure in each successive piston chamber to substantially equal the pressure in said high pressure duct between the time each piston chamber breaks communication with the low pressure duct and the time it starts direct communication with said high pressure duct, comprising:

a liquid filled pressure control chamber in said liquid handling section located between said spaced low and high pressure ducts;

`a differential pressure movable barrier traversing said control chamber and continuously dividing it into (a) a variable volume, piston chamber pressure regulating compartment, and

(b) `a separate variable volume, pressure regulation assisting compartment,

said pressure regulating compartment having an open port located to openly communicate with the open end of each successive piston chamber between the time the piston chamber breaks communication with said low pressure duct and the time the piston charnber begins direct communication with said high pressure duct, the open port of said pressure regulating compartment being so spaced from said high pressure duct that the open end of eac-h piston chamber momentarily communicates with both simultaneously as the relative movement cycle proceeds; and

duct means affording open communication between said high pressure duct and said pressure regulation assisting compartment,

whereby, during the time each piston chamber is in communication with said pressure regulating compartment, the liquid in both is subjected, through the movable barrier, to the pressure exist-ing in said high pressure duct, and vice versa, and the pressure on the liquid in each successive piston chamber is thus adjusted, prior to the start of its communication with said high pressure duct, to substantially equal the lll pressure then existing in that duct, and as each piston momentarily communicates with both the pressure regulating compartment and the high pressure duct, pressures in the pressure regulating compartment and in the pressure regulation assisting compartment are equalized, and said barrier returns to its normal position.

9. The structure described `in claim tl, and

a huid passage in the liquid handling section in communication with said high pressure duct and having an open end located between said pressure regulating compartment and said high pressure duct in a position to communicate with each piston chamber as it moves from the pressure regulating compartment to the high pressure duct, and so spaced from the pressure regulating compartment that each piston chamber, during its travel is simultaneously in communication with both the pressure regulating cornpartment and the open end of said lluid passage.

lil. The struct-ure described in claim and `a ported valve plate located `between the fixed liquid handling section and the cylinder block, and cooperating with both, and

ports in the valve plate controlling communication of the open ends of the respective piston chambers with (a) said `low pressure duct,

(b) said pressure regulating compartment,

(c) and said high pressure duct,

the ports controlling communication with the pressure regulating compartment being two in number, the rst port being nearest the low pressure duct `and lbeing a liquid metering oriiice of minute cross sectional area, and th second port being nearest the high pressure duct and being larger in'cross sectional area, the said iirst and second ports ybeing arranged in parallel and spaced sufficiently close together that the open end of each piston chamber can bridge the ports and communicate with the pressure regulating compartment through both ports simultaneously during travel from the low to the high pressure duct, as the cylinder block rotates.

il. ln a multi-cylinder, reciprocating piston type, birotational liquid pressure energy translating device which includes a housing enclosing a rotatable cylinder blocl which has a planar surface -dening the open ends of a plurality of piston chambers, and a lined liquid handling ection which has a planar surface which slidably cooperates with the planar surface of the cylinder block, which defines internally open ends of two spaced liquid handling ducts in said section, the said open ends oi said ducts being arranged and located to communicate alternately with the open ends of the respective piston chambers as the cylinder bloclt rotates in either rotational action, and in which when the cylinder block rotation is clockwise the lirst of said ducts in the liquid handling section is a high pressure duct and the second of said ducts is a low pressure duct, and when cylinder block rotation is counter'- clocirwise the second of said ducts is a high pressure duct, and the iirst duct is a low pressure duct, and in which device piston reciprocation and the rotational speed of the cylinder block is timed so that each piston travels on at least a portion of its compression strolle between the time its chamber breaks communication with toe duct of low pressure and the time its chamber begins direct communication with the duct of high pressure, regardless of the rotational direction of said cylinder block,

structure for adjusting the pressure in each successive piston chamber to substantially equal the pressure in the duct of high pressure, regardless of the rotational directionof the cylinder block, between the time each piston chamber breaks communication with the low pressure duct and the time it starts communication with the high pressure duct, comprising:

a liquid filled pressure control chamber in the liquid handling section;

a ditierential pressure movable barrier traversing said control chamber and continuously dividing it into (a) a variable v-olume, piston chamber pressure regulating compartment, and (b) a separate variable volume, pressure regulation assisting compartment, the pressure regulating compartment having an open port located in a position to communicate with the open end of each piston chamber during its travel between the two ducts in the liquid handling section;

a cylinder (35, FiG. l2) in said liquid handling scction;

a pair of passages (57, SS) connecting the opposite ends of the cylinder respectively with the two ducts (2li, 2l in. the liquid handling section;

a pair or" pas ages (till, 93) connected respectively with the opposite ends of said cylinder, each of said passages (89, 93) having an end open at the planar suriace of said liquid handling section, the two open ends being located between a respective one of said ducts (Ztl, El) and the open end of said pressure regulating compartment in positions to Vcommunicate with the open ends of the piston chambers during their travel, the respective open ends of the two passages ($9, 93) being located suhiciently near the opening of the pressure regulating compartment that cach piston chamber bridges the respective spaces between the opening (de) and the respective openings of the two passages'w?, 93);

a fitti passage (Se) connecting the central portion of said cylinder' (S5) and said pressure regulation assistinfy compartment; and

a floating plunger reciprocable in said cylinder constituting a valve responsive to the higher of the pressures in said ducts (2d, 2l), the length of the plunger being less than the distance between the respective ends of the cylinder and the respective remote edges of the said titth passage opening,

whereby when one of the ducts (2li) in the liquid handling section is the higher pressure duct, Whether the device is operating as a pump or as a motor, the plunger (Se) is forced by the higher pressure in the said duct (Sill) to the remote end of its cylinder, and blocks fluid flow through two of said passages (87, 539); and between the time each piston chamber travels from the lower pressure duct (Titi) to the higher pressure duct (2l) the pressurized liquid therein is adjusted7 through the movable barrier and the liquid on both sides thereof, to substantially equal the pressure existing in the higher pressure duct, prior to actual communication of the piston chamber with that duct;

and when toe other of said ducts (Ztl) is the higher pressure duct and the cylinder block is rotating in the opposite direction, whether' the `device is operating as a pump or as a motor, the plunger (Sd) is forced by the higher pressure to the opposite end of its cylinder and blocks tlow through the other passages (3S, 23), and pressure in each piston chamber is adjusted, while it is in communication with said pressure regulating compartment, to substantially equal the pressure in the higher pressure duct (2d), prior to actual communication of the piston chamber with that duct. Y 2. The structure described in claim l, and

ported valve plate located between the fixed liquid handling section yand the cylinder block, and cooperating with both, and

ports in the valve plate controlling communication of the open ends of the respective piston chambers with (a) said low pressure duct, (b) said pressure regulating compartment, (c) and said high pressure duct,

the ports controlling communication with the pressure regulating compartment being two in number, the rst port being nearest the low pressure duct and being a liquid metering orice of minute cross sectional area, and the second port being nearest the high pressure duct and being larger in cross sectional area, the said first and .second ports being arranged in parallel and spaced suic-iently close together that the open end of each piston chamber can bridge the ports and communicate with the pressure regulating compartment through both ports simultaneously during travel from the low to the high pressure duct, as the cylinder block rotates.

ifi

References Cited by the Examiner UNITED STATES PATENTS 1,986,584 1/35 Koplar 2310-478 X 2,529,309 11/50 Purcell 103-161 2,553,655 5/51 Herman et al. 103-162 2,661,695 12/53 Ferris 103-162 X FOREIGN PATENTS 684,551 12/ 52 Great Britain.

LAURENCE V. EFNER, Primary Examiner. 

1. IN A MULTI-CYLINDER, RECIPROCATING PISTON TYPE FLUID PRESSURE ENERGY TRANSLATING DEVICE IN WHICH THERE IS RELATIVE MOVEMENT BETWEEN A CYLINDER BLOCK AND A FLUID HANDLING SECTION WHICH DEFINES INTERNAL, SPACED, LOW AND HIGH PRESSURE DUCTS, AND IN WHICH SUCH RELATIVE MOVEMENT SUCCESSIVELY BRINGS OPEN ENDS OF THE PISTON CHAMBERS IN THE CYLINDER BLOCK INTO ALTERNATE OPEN COMMUNICATION WITH THE LOW AND THE HIGH PRESSURE DUCTS IN THE FLUID HANDLING SECTION, AND IN WHICH PISTON RECIPREOCATION AND THE RELATIVE MOVEMENT BETWEEN THE CYLINDER BLOCK AND SAID FLUID HANDLING SECTION IS TIMED SO THAT EACH PISTON TRAVELS ON AT LEAST A PORTION OF ITS COMPRESSION STROKE BETWEEN THE TIME ITS CHAMBER BREAKS COMMUNICATION WITH SAID LOW PRESSURE DUCT AND THE TIME ITS CHAMBER BEGINS DIRECT COMMUNICATION WITH SAID HIGH PRESSURE DUCT, STRUCTURE FOR ADJUSTING THE PRESSURE IN EACH SUCCESSIVE PISTON CHAMBER TO SUBSTANTIALLY EQUAL THE PRESSURE IN SAID HIGH PRESSURE DUCT BETWEEN THE TIME EACH PISTON CHAMBER BREAKS COMMUNICATION WITH LOW PRESSURE DUCT AND THE TIME IT STARTS COMMUNICATION WITH SAID HIGH PRESSURE DUCT, COMPRISING: A LIQUID FILLED PRESSURE CONTROL CHAMBER LOCATED BETWEEN SAID LOW AND HIGH PRESSURE DUCTS DEFINED BY THE SAID FLUID HANDLING SECTION; A DIFFERENTIAL PRESSURE MOVABLE BARRIER TRAVERSING SAID CONTROL CHAMBER AND CONTINUOUSLY DIVIDING IT INTO (A) A VARIABLE VOLUME, PISTON CHAMBER PRESSURE REGULATING COMPARTMENT, AND (B) A SEPARATE VARIABLE VOLUME, PRESSURE REGULATION ASSISTING COMPARTMENT, SAID PRESSURE REGULATING COMPARTMENT HAVING AN OPEN PORT LOCATED TO OPENLY COMMUNICATE WITH THE OPEN END OF EACH SUCCESSIVE PISTON CHAMBER BETWEEN THE TIME THE PISTON CHAMBER BREAKS COMMUNICATION WITH SAID LOW PRESSURE DUCT AND THE TIME THE PISTON CHAMBER BEING DIRECT COMMUNICATION WITH SAID HIGH PRESSURE DUCT; AND DUCT MEANS AFFORDING OPEN COMMUNICATION BETWEEN SAID HIGH PRESSURE DUCT AND SAID PRESSURE REGULATION ASSISTING COMPARTMENT, WHEREBY, DURING THE TIME EACH PISTON CHAMBER IS IN COMMUNICATION WITH SAID PRESSURE REGULATING COMPARTMENT, THE LIQUID IN BOTH IS SUBJECTED, THROUGH THE MOVABLE BARRIER, TO THE PRESSURE EXISTING IN SAID HIGH PRESSURE DUCT, AND VICE VERSA, AND THE PRESSURE ON THE LIQUID IN EACH SUCCESSIVE PISTON CHAMBER IS THUS ADJUSTED, PRIOR TO THE START OF ITS COMMUNICATION WITH SAID HIGH PRESSURE DUCT, TO SUBSTANTIALLY EQUAL THE PRESSURE THEN EXISTING IN THAT DUCT. 